GREASE (ZERK) FITTINGS: Unlike the newer American
"low-maintenance" cars, the Jag has zerk fittings all over
the suspension. Periodically it should be gone over with the
grease gun, but please be conservative. It is tempting to
grease fittings too often and to pump too much grease, which
will destroy the seals or gaiters on the joint.

The following is a list of the grease fittings on the
car:

All six universal joints -- good luck getting at
the forward one on
the drive shaft. The protective covers on the rear
axle U-joints have openings for greasing, but they may
not line up. You can relocate them as necessary.

All four corners of the flat plate under the
differential (lower swingarm inner joints). There are
holes in the plate for access to the zerk fittings.

The needle bearings in the lower pivot joint of the
rear hub carriers; the fittings are just inside the rear
wheels at the bottom.

Both front hubs. The fitting is on the side of the
hub near the outer cap. With some wheel designs, the
wheels do not need to be removed. Rumor has it these
fittings have been deleted in later cars.

Both upper front ball joints -- remove the front
wheels for access.

Both lower front ball joints. The fittings point
inward, underneath the car.

Also, the rear wheel bearings should be greased by
removing the small cap on the hub carrier and spooning a
little grease into the hole. Don't overgrease, because the
excess merely spins out and coats the inside of your
wheels.

The pre-1983 Jaguars also had zerk fittings on the tie
rod ends, but the later cars were fitted with "improved" tie
rod ends with no such fittings.

The ball joint zerk fittings are designed with a relief
system to prevent the grease gun from applying too much
pressure. Under the fitting itself is a plastic washer that
covers the relief hole. When the joint is full of grease,
any additional greasing will force the plastic washer to
bend, allowing the grease to come out adjacent to the
fitting itself.

Michael Neal sends this tip on lubricating the lower ball
joint: "If the grease comes out from behind the plastic
washer as soon as you apply it then the passage is plugged.
The best way to clean the passage is to remove the lower
plate and zerk fitting. Ream out the passage and apply some
grease to the cup before reassembling. The grease in the
passage hardens after a relatively short amount of time and
plugs the passage."

When installing the zerk fittings on these ball joints,
note that overtightening the fitting onto the plastic washer
will deform the washer and open the relief hole.

Don't overlook the zerk fittings themselves as a possible
source of trouble. Each zerk fitting has a tiny
spring-loaded ball check valve to allow grease in but not
out. It is susceptible to corrosion and jamming. They are
also easily damaged by impact.

RIDE HEIGHT: XJ-S owners are often concerned about
whether the car is actually supposed to sit that low, or if
something is wrong. The Jaguar XJ-S Repair Operation Manual
describes a check, but it assumes you have original tires
with full tread. It also assumes you have "slip plates",
devices you set the front tires on so they can slide around
and not bind the suspension travel. The following is a
derived procedure that subtracts the tire rolling diameter
out of the equation in order to determine if your car is
sitting at the "correct" ride height for the tires you have
on it, and all it requires is a level section of
concrete.

Position the car on level ground with nobody in it, no
heavy stuff inside or in the trunk, a full tank of gas, the
emergency brake off and the shifter in N. Push the car back
and forth a few feet. When pushing rearwards, push on the
front bumper and deliberately bounce the front of the car a
little while pushing. When pushing forwards, push the rear
bumper and deliberately bounce that end as well. This is to
make sure the car is fully settled in its position.

Measure the height to the center of the front wheels.
With any luck, they should be the same, but if they vary
slightly determine the average.

Subtract 6-3/8" from this height. This gives you the
correct height above the ground for the flat bottom of the
cross member between the front wheels.

Using the same front wheel center measurement (do
not measure the height of the center of the rear
wheels), subtract 4-7/8". This will give you the correct
height above the ground for the edges of the plate between
the rear wheels with a full tank of gas.

So much for the "correct" ride height. Now, to describe
what you actually have, a story from B. J. Kroppe: "My
former supervisor (a Jaguar employee) did vehicle packaging
for the F-Type. He started with XJ-S drawings and came
across some things which didn't add up. So he went to the
assembly plant and measured some XJ-S vehicles and compared
them to the drawings. He discovered that the cars being
produced (this was mid-late 1980's) were very much lower
than the drawings said they should be.

"After some investigating he learned that over the years
more features had been put on the car, making it heavier,
but springs had not been changed to accommodate for the
added weight, thus causing the lower ride height in the
actual cars vs. what the drawings were saying."

In practice, it appears the XJ-S may ride about a half
inch lower than the "correct" ride height, even when new. If
yours is significantly lower than that, however, it's
probable that either the shocks or the springs need
replacing.

SAGGING FRONT END: If your Jag seems to be riding
low on the nose end, a likely culprit to check is the front
shock absorbers. The XJ-S uses gas shocks, in which the
damping fluid is held under pressure by a small amount of
gas within the chamber. A side effect is that the pressure
causes the shock to try to extend. This extending force
helps raise the car a little, especially when the suspension
is soft. The Jag was designed for these shocks, and if they
lose pressure, the nose sags. Since the pressure may be lost
while the fluid is still present, the low nose may be the
first sign of failing shocks. Of course, the rear shocks are
also gas type and may cause the same problem, but it doesn't
seem to happen as often.

SHOCK ABSORBERS: To check the front shocks, jack
up the car and remove the front wheel. From inside the
engine compartment, remove the locknut, nut, rubber doughnut
and seat from the top of the shock absorber. Then reach into
the wheel well, grab the top portion of the shock and pull
it downward. If it is in good shape, it should move downward
smoothly with a hiss, and when released should move smoothly
but forcefully back to its full extended position by itself.
If the motion is not smooth, or the shock compresses easily
and quickly with no damping effect, or fails to extend
itself when released, replace the shocks.

The traditional tests of shock absorbers involving
pushing the car down and noting its recovery or noting the
car's reactions over bumps are not entirely applicable to
modern gas shocks. If a gas shock loses its gas charge, it
may still appear to pass these tests; if it still has fluid
in it, it will still provide some damping. The damping
effectiveness is greatly reduced, however, and will get much
worse over a series of bumps. And, as noted above, the car's
ride height will be affected. There seems to be no
substitute for disconnecting the shocks and checking them by
hand. Checking the rear shocks will require a spring
compressor to remove the springs from the shocks.

The front shocks should be checked before having the car
aligned. The front end of the car sitting lower than it
should has an effect on the camber, and will alter alignment
settings.

CLUNKS -- FRONT: If something in the front goes
"clunk" when you drive over a bump, check the rubber
bushings on the top of the front shock absorbers. British
non-metallics again. Any generic rubber shock bushing will
do, and will do better than the original. David Littlefield
says, "Generic replacement bushings are available in the
"Help!" section of your local auto parts store. Look for the
area with a variety of parts on red cards. The part number
is 31018 and they come two to a pack. The pack also says
"Ford/Mercury" on it, so if you can't find the "Help!"
products, perhaps you can ask for a Ford/Mercury
replacement. You will need two cards (or four bushings
altogether). I paid $2.58 per card at Pep Boys. I would
describe them as being about the size and shape of a medium
sized mushroom cap; only, of course, with a hole through the
center.

"Replacement is a breeze. I did both sides in a little
over an hour. The biggest operations are jacking up the car,
removing the tire, and removing the hinged side of the air
filter on each side. Removing the old bushings and
installing the new ones is a straightforward and simple
procedure." Note: you can easily compress and release the
shock while you're there, thereby checking that it's in good
shape -- see above.

"The old bushings were the consistency of foam rubber
after five years and about 25,000 miles. These were Jaguar
replacements done after the car had traveled 32,000 miles
over four years on the factory installed bushings.

"Bottom line: About $5.00 and an hour and a half of my
time for a fix that should hopefully last a long, long time.
This versus about $25 in parts and $75+ in labor to the
dealer for a fix that would last, at most, about 30,000
miles."

Note that the XJ-S has steel washers that fit between the
bushings and the chassis; purpose unknown, but it won't hurt
to put them back in with the new bushings. Littlefield says,
"The real purpose of the washers seems to be to let you know
your bushings are bad by clanking around and driving you
nuts until you replace them!"

Another common cause of clunks is loose diagonal supports
across the top of the engine compartment. Make sure the
bolts at both ends are tight.

Also check for a failed subframe mount. When the rubber
within the mount is torn but still in place it would seem
that it shouldn't make any sound, but it does. There are two
doughnut-shaped mounts at the front, and two V-shaped mounts
near the steering rack. If the rubber is torn or otherwise
damaged, they should be replaced.

FRONT SUSPENSION CHECK: You may be confident that
your front suspension is just fine, but this test is so
quick and easy you might as well try it. Stand beside the
car and grab the top of a front tire and shake it vigorously
in and out. If everything is OK, the only thing you will
feel is the flexing of the tires, and you will hear
nothing.

If you feel any slop, or you hear a "clunk" back and
forth, your front suspension is not up to snuff. You
should check the following items, which are discussed in
more detail below:

Adjustment of the wheel bearings.

Condition of the ball joints, upper and lower.

Wear groove on bottom of front axle.

Bushings at inner end of upper and lower
swingarms.

Front subframe mounts.

Perform this test and correct any problems noted before
having your car aligned. The repair or replacement of ball
joints, tie rod ends, swingarm bushings or subframe mounts
normally requires realignment, and it's a shame to have to
do it over.

It should also be noted that, contrary to common belief,
a car will not periodically require realignment for no good
reason. If a car was correctly aligned at one time and no
longer is, it is because parts are either worn or damaged,
and merely realigning without addressing those parts is
unwise.

FRONT HUB REMOVAL: Michael Neal suggests the brake
caliper not be removed when pulling the hub, to avoid
fiddling with steering arm
shims. Instead, unbolt the disk from the hub by
inserting a socket through an opening in the dust shield.
Then, remove the hub leaving the disk in place.

FRONT WHEEL BEARINGS: According to Chad Bolles,
the XJ-S uses standard front wheel bearings, available in
any auto parts store. The pre-1977‡ XJ-S outer is an A-2,
the inner is an A-6. The 1977‡-up car uses A-13 for the
inner, A-12 for the outer.

FRONT WHEEL BEARINGS/SEALS SERVICE INTERVAL --
ABS-EQUIPPED CARS: Bruce Segal reports from Canada:
"Jaguar was recommending that the front wheel bearing seals
be replaced every 15,000 mi (24,000k). At the same time the
bearings should be looked at and replaced if there is any
evidence of water ingress. I don't know if this applied
anywhere besides Canada. We found that after going to this
procedure front wheel bearing failures disappeared."

Stefan Schulz provides a possible explanation: "It could
well be the likelihood of contaminant ingress that causes
Jaguar to specify the change interval. The grease seal at
the inside of the front hubs was changed with the advent of
ABS. The pre-ABS grease seal looks like it will properly do
the job, since it sits firm in the hub casing and its
sealing lip rotates (and presumably experiences friction and
wear) over the relatively smooth surface of the stub axle.
The post-ABS grease seal works the other way round, it sits
on the hub carrier and its lip touches the hub proper which
rotates relative to it. The hub's inside surface in that
area is nothing like as smooth as the sub axle's surface, so
I'd expect that grease seal to fail much earlier."

"I have had my XJ-S for almost three years and 42,000
miles now. R&R'd stub axles and front wheel bearings
when I bought it and bearings again about 10,000 miles ago.
They needed it."

Segal again: "In my environment (winter, salt, water )
the new type seals do not provide a long term solution --
thus Jaguar Canada's very short replacement recommendation.
We've found that quite often the bearings had started to
rust front the salt water getting past the seal."

If you have an ABS-equipped car, perhaps while you have
the hub off for an overhaul it'd be a good idea to polish up
the contact surface on the inside of the hub to help seal
life.

FRONT AXLE WEAR: The inner races of the inner
front wheel bearings tend to turn on the axles. As a result,
they eventually wear a groove in the axle, on the bottom
where the load is. This allows the wheel to wobble even when
the bearings are adjusted properly, and your Jag starts
driving like a Pontiac.

To check for problems, remove the front hubs and check
the stub axles for a wear groove. Run your fingernail along
the bottom of the axle from the upright outward. If your
fingernail catches at all, the axle should be replaced.

When assembling, ensure that the inner races will not
turn by using Loctite 640 or some similar high-strength
bearing retaining substance. Use it on the inner race of the
outer bearing, too, since it has been known to have the same
problem. Adjust the front wheel bearings as described
below.

FRONT WHEEL BEARING ADJUSTMENT: Spin on the
retaining nut until it seats, normally a very sudden change;
continue to tighten while turning the hub until an
increase in resistance in turning the hub is felt. This is
usually about 1/10 of a turn after the adjustment nut starts
to seat.

This may seem tight, and in fact may be tighter than the
official Jaguar procedure (measuring end play) would result
in. Any bearing expert will tell you that proper operation
of a roller bearing requires some preload. It is better to
be too tight than too loose. When tight, the weight of the
car is distributed among the rollers. When loose, the slop
allows the load to be taken by only one or two rollers at a
time, and the unloaded rollers may slide rather than
roll.

Note that having the bearings adjusted too loosely -- as
well as having a grooved front axle, as described above --
would be detrimental to seal life. And the seals on the
ABS-equipped cars may be marginal already, as mentioned
above.

FRONT WHEEL BEARING CAPS: Apparently, some bearing
caps are a total seal, while others have a small hole in the
middle. It is suggested that if you have wheels that don't
keep dirt out of this area, put a small piece of aluminum
tape over the hole. Or, just pry it off and take it down to
the local auto parts store and buy a generic
replacement.

CHECKING OF BALL JOINTS AND TIE ROD ENDS: To test
joints such as these, it is helpful to find a convenient way
to "shake" them, or to move them in such a way that will
cause them to slop one way and then the other. In the case
of tie rod ends, this is easily done by moving the steering
wheel back and forth just a little. With ball joints, if the
front tire shaking described above caused a "clunk", that
same motion will work for this test.

This test requires two people. Place a single finger on
the joint in question in such a way that one side of the
finger is against the hardware on one side of the joint, and
the other side of the finger is against the other side.
While holding this position (may be difficult, since the car
should be sitting on its wheels) another person should
provide the shaking motion. If the joint is OK, no motion
can be felt between the two parts. If the joint is loose, a
human finger will easily detect the slop. Typically, any
slop at all is unacceptable, the joint should be
replaced.

ANTI-SEIZE COMPOUND: See description earlier.
This note is to point out that many suspension components
involve tapered fits, such as the ball joints and the front
axle in the upright. It is suggested that anti-seize
compound be used on the tapers themselves as well as the
threaded nuts. It does no harm, and can make the assembly
much easier to get apart in the future. In tapered fit
applications, care should be taken to ensure the entire
fitting is thinly coated, since the anti-seize compound will
not be spread during assembly as it is on threads.

FRONT SPRING COMPRESSION: If you're gonna fiddle
with the lower ball joints, you need to be careful with that
spring. Ideally, you should use a spring compressor that
fits this assembly, but that may be difficult to find -- the
front spring mounts on the XJ-S seem designed to confound
most standard spring compressors. The official Jaguar tool
is a threaded device that goes up the middle, so perhaps
something can be rigged involving some threaded rod. Other
suggestions include tying the suspension in the loaded
position while it's sitting on it's wheels and then
jacking it up -- please be very careful tying it, and make
good and sure whatever you use is strong enough for the job.
And keep your body parts outta the way anyway, just in case
it breaks loose.

Another idea is to gradually unbolt the spring pan from
the A-arm, replacing the bolts with progressively longer
bolts until the spring pan is far enough below the A-arm
that it is completely unloaded. Then the spring can be
removed altogether. Works, but is very time-consuming and
requires a lot of bolts of various lengths.

Others prefer to jack up the car under the lower A-arm
itself, thereby keeping it loaded while you're working on
the ball joint. Works, but be sure the spring plate can't
slide off the jack while you're trying to get the ball joint
to break loose. Dale Knaus says, "The way I change the ball
joints is to start by blocking the opposite rear corner of
the car at the jack point, and raising the wheel I am to
work on by jacking under the spring pan on the lower
A-frame. By blocking under the opposite rear, the jack will
lift more of the car and compress the spring more."

LOWER BALL JOINTS: The original lower ball joint
is a rebuildable assembly, with parts books listing the
individual components. The lower ball joint from the XJ40
(the 1988-on boxy XJ6) is a one-piece throwaway item (part
number CAC9937) that will replace the entire ball joint
assembly on the XJ-S, and costs less than the individual
parts of the original design. In fact, Jaguar no longer
makes the original, rebuildable ball joint or parts to fit
it; the authorized repair shops merely replace the joint
with the XJ40 item.

An aftermarket parts company, Quinton Hazell, makes a
rebuild kit for the original lower ball joint assembly. QH's
prices for this kit are much more reasonable than the Jaguar
parts prices ever were, and it is cheaper to use this kit to
rebuild your ball joint than to install the new XJ40
unit.

The lower ball joint is assembled with shims to provide a
properly snug fit between the ball and the socket. However,
it should be noted that these shims are intended to provide
a proper fit at assembly, not for removing the slop
from a worn joint. If a joint develops slop, it should be
rebuilt with new parts or replaced entirely, not merely
readjusted.

When rebuilding the lower ball joint, don't lose the
shims that come out. Although the QH kit includes shims,
they are really intended to provide some adjustment
capability from the original set; there may not be enough to
provide all new shims.

When rebuilding the ball joint, thoroughly grease the
ball and socket parts prior to final assembly. Although the
joint has a zerk fitting, its use is no substitute for
proper greasing at assembly.

The gaiter on the original Jaguar ball joint is a Rube
Goldberg assembly in itself, and the parts are available
separately. The gaiter itself is a clear flexible plastic
item, with a steel ring molded into it to make the small
opening fit snugly around the ball shaft. The gaiter fits
into a plastic ring (C22970), and a rubber ring (looks like
a skinny O-ring) fits into a groove on the gaiter to hold it
snugly into this plastic ring. The plastic ring then snaps
onto the ball joint. Be sure that the plastic ring is
oriented properly; the little ridge on the inside must be on
the edge toward the joint itself. It appears that the
intention of all this complexity is to allow the gaiter to
turn with respect to the ball joint as the steering is
turned, rather than twisting the gaiter or allowing the
small end to turn around the ball shaft; the plastic ring is
expected to rotate in the groove on the ball joint.

The gaiter provided in the QH rebuild kit is different
than the original. It is a more conventional solid black
rubber item with no metal reinforcement. A metal clip is
provided in the kit to be used in place of the rubber ring
on the large opening. The kit does not include the
plastic ring; if you boogered up the original getting it
apart, it can be ordered separately. In a pinch, the gaiter
seems to work just as well attached directly to the socket
without the plastic ring.

If you are replacing just the gaiter itself and have
neither the metal clip nor the rubber ring, you can simply
tie it on with some wire. If using the QH gaiter, you can
use nothing at all -- the black rubber gaiter fits quite
snugly.

The original Jaguar gaiter has a life expectancy of less
than five years. The clear plastic turns dark brown, then
rots and falls out in crumbs. However, the gaiters in the QH
kit are also British, so there's no telling if they are any
better than the originals.

The ball shaft must be separated from the lower A-arm to
replace the gaiter. Disconnect the upper ball joint to allow
tilting the upright to get better access. Use of a fork-type
ball joint separator on the lower joint will not only
destroy the old gaiter, but the plastic ring and the upper
ball seat as well. The fork type separator doesn't work very
well here anyway; better to have the screw-type separator on
hand. If the joint isn't jammed too severely, it is also
possible to get the joint loose by disconnecting the tie rod
and the brake line (helpful for getting the nut off anyway),
jamming something between the inner edge of the hub carrier
and the A-arm, and forcefully rocking the hub carrier
outward.

UPPER BALL JOINT: The official repair manual calls
for "Steering Joint Taper Separator JD.24", but we don't
need no steenking separator! Put the car on jackstands and
remove the wheel. Put a jack and block of wood under the
lower ball joint and jack it enough that the rubber bumpers
on the upper A-arm are not touching the subframe. Loosen the
nut on the upper ball post several turns, but do not
remove it. Lower the jack so that the rubber bumpers sit on
the stops and the full spring force is applied to separating
the joint. If you're lucky and the previous mechanic used
anti-seize compound on the taper, you'll hear a pop as it
comes loose. If more difficult, a little judicious tapping
on the side of the upright may help.

Make sure to note where the shims are located between the
arms and the ball joint. Even if you plan to have the car
aligned, at least it will drive better on the way to the
shop. The shims are supposed to lift right out, but they
weren't made quite right. They tend to catch the bolt on the
inner corner on the hook-shaped end. If this corner is filed
slightly, reassembly will be easier.

The gaiter and associated parts on the upper ball joint
are exactly the same parts as those on the lower joint --
see notes above.

FRONT SWINGARM BUSHINGS: The front swingarm
bushings may be checked using similar methods as the ball
joints, except that the bushings include some rubber so
there will be some slight motion even in a perfectly good
joint. Usually, the best indication that a swingarm bushing
is bad is that some of the rubber is hanging out of it.

Steering

STEERING ARM SHIM: The
steering arm bolts to the hub carrier with two bolts. At the
rear (longer) bolt, there is a shim (it looks like a washer)
that goes between the steering arm and the brake caliper.
Don't lose it! Omitting this shim at reassembly
screws up your alignment and distorts your suspension
parts.

If you have lost the shim already, replacements are
available in .004" and .010" thicknesses. To determine the
thickness required, assemble the parts and tighten all bolts
except the one the shim goes on. Measure the gap between the
brake caliper and the steering arm with a feeler gauge.
After assembly with the appropriate shims, be sure to have
the car aligned.

ALIGNMENT: First off, note that while many cars
are aligned only at the front, the XJ-S requires that all
four wheels be aligned. Although there is really only one
adjustment at the rear (camber), it is likely to take most
of the mechanic's time if any adjustment is necessary; it
requires that the driveshafts be unbolted from the
differential unit and shims changed.

Randy Wilson sends a warning to be careful which
alignment shop you choose to align a Jaguar: "The generic
American tank has shims to align the front suspension camber
and castor. These shims are placed at both the front and
rear pivots of the upper control arm. By adding or
subtracting shims equally at both ends, you change the
camber. By adding or subtracting shims at one end only, you
change the castor. Jaguars do not work this way, but look
like they do to the uninitiated. The Jaguar has shims at the
upper pivot just like the Chevy/Ford above, but they must be
used as camber adjustment only with equal amounts of shim
change at both front and rear pivots. The castor adjustment
is done by a separate set of shims at the upper ball joint.
If some hack jumps in there and adjusts camber and castor by
staggering the pivot shims, you will end up with a car with
a sort of correct alignment (dynamic castor gain will not be
as Jag intended), but the car will just eat upper control
arm bushings.

"The good news is that the XJ front subframe is one stout
critter. Unless it has been seriously whacked, it is rare
for camber or castor to need adjusting. Alignment is usually
just a matter of setting the toe correctly after the latest
steering rack change/rebuild."

There are reports that the spec books in the alignment
shops consistently list the wrong alignment specs for
Jaguars. Just to be sure, take your own repair manual with
you, and if the numbers that you have disagree with those
they have, insist they use yours. They shouldn't care, it's
your car and your money.

There are some reports that the alignment of the XJ-S
really needs to be done according to the procedures outlined
in section 57.65.04 of the Repair Operation Manual --
namely, that the ride height must be restrained at a
specified position for the alignment. The standard alignment
shop shortcut of aligning the car at whatever ride height it
sits at is not acceptable; both the front and the IRS
geometries change with ride height, and many (most?) XJ-S's
don't sit at the correct ride height by themselves. Failure
to establish the correct ride height during alignment
reportedly may result in a shaking in the front end at 50-60
mph -- a notorious problem in the H&E convertible,
perhaps because the H&E convertible is also notorious
for a low ride height.

If you're gonna pay your money for an alignment, you
might as well insist it's done properly. Of course, it's not
likely the alignment shop you choose will have the special
tools used to establish the ride height on Jaguars -- unless
you go to a dealer. So, if you're going someplace other than
the dealer for the alignment, you'd be well advised to take
the tools with you -- and the instructions from the repair
manual showing how they're used.

The tools for setting the ride height of the front
suspension are made from short lengths of tubing, and
there's enough info to make them provided in section
57.65.04 of the Repair Operation Manual. The tools for
setting the ride height of the rear suspension are a pair of
metal hooks, and are described only as Jaguar tool no.
JD.25. These would be even easier to make than the tubes, if
only you knew what the key dimension was -- and just what is
this book for, anyway?
Figure
9 should provide the info needed about theJaguar
Alignment Tool JD.25

Note that although the official Jaguar tools are made
from a single 9/32" steel rod suitably bent, there's no
reason you shouldn't be able to screw together suitable
tools from eye bolts, threaded hooks, threaded rod, and some
coupling nuts -- all available at any hardware store for
peanuts. Remember that you'll need to make two.

These tools might actually be a suitable thing for local
Jaguar clubs to keep on hand for the benefit of their
members. Apparently, these exact same tools have been used
on all Jaguars that use the same IRS as the XJ-S -- which
means all E-types, all XJ6/12 SI/II/III -- basically all
Jaguars made for about four decades. In fact, the dimension
shown in the drawing was provided by Michel Carpentier, who
got it from a Mk10 service manual. At the time the Mk10 was
made, the tool was called a J25; the tool names were changed
to JD after Jaguar bought Daimler.

Note that when either end of a Jaguar is being
aligned, the ride height setting tools should be in place on
both ends.

In what must be considered a serious shortcoming, the
Haynes manual does not discuss this ride height setting
procedure at all, and lists an incorrect tool number (JD21
-- actually the number for a bushing tool of some sort)
without going into any detail about using it. It suggests
that alignment is not for the home mechanic, but provides a
few generic guidelines for what is done -- just enough to
get you in trouble. If you have only the Haynes manual, it
is recommended that you obtain a copy of the alignment
instructions from a Jaguar manual before having an alignment
done by a non-Jaguar shop.

Finally, note that most of the above info probably
applies only to the pre-1993 XJ-S with inboard rear brakes.
From 1994 on, a completely different IRS was used with
outboard brakes, and it presumably requires different
alignment procedures.

STEERING COLUMN INSTALLATION: If you have lowered
your steering column, Rob Reilly sends this tip for
reinstallation: "When putting back the steering column use a
little rubber cement to hold all the washers in place. Leave
the bolts loose and pull the column back about 1/4" before
you tighten them; if you don't, you will get binding in the
lower column universal joint and bumpy steering."

STEERING RACK LUBRICATION:
According to the John's Cars catalog, using the zerk fitting
on the steering rack does more harm than good, and they
remove them during their rebuilds. Others have reported no
problems, but obviously one would be well advised not to get
carried away with the grease gun. Stefan Schulz reports:
"Perhaps even Jaguar realized that eventually, mine
(CBC5708) doesn't have that fitting any more."

STEERING RACK LOWERING: The steering rack is
mounted on slotted holes, so that either end can be
repositioned up or down. The intent is to be able to
position the rack properly with respect to the lower A-arm
mounts, and there is a special Jaguar tool used to check for
proper position when reinstalling. Presuming that you don't
happen to have this tool laying around the house, it is
suggested that you carefully mark the position of the
mounting bolts within the slotted holes prior to lowering
the rack. When reinstalling, simply put it back where it
was.

Any time the steering rack is lowered for inspection or
repair, it is wise to disconnect the bolts mounting the
power steering cooler to the subframe. The pipes on this
unit are very fragile, the hoses are short and often
stiffened by age and heat, and a new cooler is of course
more than $100. It can generally be repaired by any
reputable radiator shop, however.

STEERING RACK MOUNT BUSHINGS: The mount bushings
in the steering rack are parallel to the axis of the rack
itself. Since the forces caused by steering are also
parallel to the rack, the elastomer in the bushings is
subjected to shear. This is a really lousy design; sound
engineering practice is to avoid shear or tensile stresses
in elastomers, and subject them to compressive loads
only.

This book is organized such that this section covers
maintenance only, modifications are later in the book. Many
people probably feel that they do not wish to modify their
car, and may not even read through that section. Please,
please take the advice on replacing
these rack mount bushings. Even if the stock bushings
have not yet failed, even if the car is brand new, it is
advised to replace them with alternative design
bushings.

Contrary to the instructions in the manual, the steering
rack can be lowered far enough to work on the mount bushings
without disconnecting either the hydraulic lines, the tie
rods or the steering column. The only difficult part is
access to both ends of the three mounting bolts.

John's Cars offers a rental tool for removing the
original bushings from the rack. It is extremely helpful,
especially when working with the rack hanging under the car
where a bench press won't help. Or, you can improvise such a
tool using two 3/8" drive sockets (one with an OD a hair
smaller than the bushing, one deep and large enough for the
bushing to fit inside it), a long 5/16" bolt or piece of
threaded rod with nuts and washers.

A method to avoid: Some people cut the rubber and center
sleeve out, leaving only the outer sleeve, then insert a
hacksaw and cut through the sleeve on one side; the sleeve
can then be collapsed and removed easily. If done carefully
enough, it appears to work fine, but a small nick on the
aluminum boss on the rack can cause a stress crack later.
Using a drill or other means to destroy the original bushing
involves similar risks.

Another method to avoid: using a hammer. You're just
asking for damage to that aluminum.

An obvious method to avoid: Heating the aluminum up to
get the bushings loose. Unbelieveable as it may seem, some
people are willing to try this. The facts that the housing
is aluminum which conducts heat very well, the seals
inside are rubber, and a rebuild costs as much as a
three-day ocean cruise for two never occurs to them.

The stock assembly includes a sheet metal U-channel that
fits around both bushing assemblies on the driver's side,
holding the whole mess together as you offer it up to the
car. When you lower the rack, this piece might stay up
there; pull it out, it's helpful for installation. The
aftermarket bushing set from John's Cars includes a new one
of these pieces -- very nice, since the old one might be a
little mangled.

Be sure that all rack mount parts fit snugly when
assembled. Do not use the bolts to pull the frame in to meet
the sides of the bushings. If necessary, buy some 5/16"
fender washers and insert them alongside the mounts to make
them fit properly.

STEERING RACK MOUNT BOLTS: If you happen to be
working on the rack with either the engine or the front
subframe out of the car, you may be able to put the bolts in
any way you wish. But for the benefit of those who work on
the car later, please install the upper mount bolt on the
driver's side from the outside inward, and the lower bolts
on both sides from the inside outward. This makes it much
easier to install or remove the rack with the engine and
front suspension in the way.

If you must replace the mounting bolts, be careful not to
use bolts that are too long. When complete, be sure the
upper bolt on the driver's side does not protrude too close
to the engine block, since the engine moves on its mounts
and will beat against the bolt. And the lower bolts should
not protrude too closely to the lower A-arms, since they are
likewise mounted on rubber and may move during
operation.

STEERING RACK REMOVAL: If you have to totally
remove the steering rack, one problem is how to remove the
pinch bolt that connects the steering column swivel joint to
the tower shaft. Remove the oil filter first, then turn the
steering wheel until the pinch bolt is positioned where you
can get at it.

Also note that the pinch bolt must be completely removed
for the swivel joint to be disconnected from the tower
shaft. The tower shaft has a recess the bolt fits through;
merely loosening it will not permit removal.

You might find it helpful to carefully mark the relative
position of these parts prior to disassembly.

STEERING RACK TUBE CHAFING: Stefan Schulz reports
on chafing problems on his RHD car: "...above the rack on
the left is where the pipes go to the power steering pump.
On mine there is a designed-in problem where one of the
pipes chafes against a bolt head. This cost me two
replacement pipes before I figured out what was going on. No
way to get around it with the Jaguar original parts.

"My steering rack is a CBC5708N, which is the UK (RHD)
sports pack rack. The pipe is part of the high pressure hose
assembly CAC3654 (same as the plain XJ-S). Calling it either
hose or pipe is misleading because it consists of
alternating sections of hose and pipe.

"One of the pipe sections either constantly chafes on or
occasionally rubs against a bolt head near the upper left
side of the rack, as seen from underneath the car facing
forward. The severity of the chafe will depend to some
extent on how much either end of the hose assembly is
twisted against its fittings during installation. The design
fault appears to lie in the fact that the offending section
of pipe is dead straight (which is cheap) as opposed to
having a slight bend to clear it (which costs at least an
extra GBP0.02 to manufacture).

"Funnily enough, inspection of hoses and pipes for chafes
is a part of the 7,500 miles maintenance schedule. No
prizes for guessing why, in case any more such design gems
lurk in the car.

"My workaround, which operates entirely satisfactorily,
is to put a hose clip around the chafing area of the pipe,
to check it every time I get under the car and to replace it
when necessary. So far I only needed to do it once, after
about two years of service. The pipe still is as new.

"A hydraulics shop could easily make up a properly formed
section of pipe, probably at a fraction of the cost of a
Jaguar original as well."

STEERING RACK TOWER SHAFT SEAL: This seal is prone
to leakage. John's Cars offers an aftermarket seal that is
supposedly better than the original. It better be, it's
quite expensive.

Reportedly, one problem associated with this seal is
incorrect installation by driving it too far into the
housing. Be sure not to drive it any deeper than it needs to
go.

STEERING RACK REBUILDING: There is a "seal kit"
available for the steering rack. Note that reportedly the
tower shaft seal is not included in this kit; check
with your source and order the tower shaft seal separately
if necessary.

A high percentage of people who have rebuilt their own
steering racks have reported failure on the first try, and
all for the same reason: when installing the rack bar
through the seal on the driver's side end of the rack, the
teeth on the rack bar ruined the seal. This typically
results in ordering an entire new seal kit to obtain this
one seal, and greater care the next try. The repair manual
calls for wrapping the rack with tape prior to sliding the
seal over it; apparently this is the minimal precaution,
experience says to lube it up as well and exercise extreme
caution during assembly. It has also been suggested that the
seal and the part it mounts into be slid over the rack
separately and then assembled, since installation in the
housing makes the seal more difficult to work with.

STEERING WHEEL ALIGNMENT: If your steering wheel
is cockeyed when driving in a straight line, your problem
may be in the relationship between the steering wheel and
the rack, or between the rack and the front wheels. Jaguar
has provided a nifty method of determining which. If you
remove the grease fitting from the steering rack, a dowel
(or special Jaguar tool no. 12279) can be inserted to engage
a notch in the rack. When the notch is lined up with the
grease fitting hole, the rack is centered. The steering
wheel can then be lined up properly. Once this is done, a
misalignment when driving straight (be sure you're on a
level road, and not in the right lane of a road that is
crowned) calls for correction at the tie rods. If the
correction is minor and you are confident that the alignment
is otherwise OK, this can be done by carefully marking both
tie rods and adjusting both of them the same amount.

TURNING RADIUS: Dan Jensen reports, "I recently
replaced the power steering racks in my '83 XJ6 and '84 XJ-S
with rebuilt units. After changeout, I noticed a
significant, and undesirable, increase in the turning radius
on the XJ6. This often made it difficult to make U-turns
without backing up, and complicated parking. A check with my
local Jag specialist revealed the source of the problem.
Some point along the line, Jag added rack travel limiters as
part of the inner ball joint lock tabs. These were
apparently installed to preclude potential rubbing of the
tires on front end components after Jaguar changed the
recommended tire size from 205/70 to 215/70. I don't know if
this applied to the XJ-S as well, which had 215/70s
specified. By pulling back the inner ends of the rack boots,
I could see the thicker locking tabs. I unscrewed the inner
ball joints and replaced the wide tabs with the narrower
tabs. This caused no noticeable change in toe-in since the
thickness of the locking tab between the rack and ball joint
is the same on both varieties of tabs. This was a 10 minute
job and fully restored the tighter turning radius I was used
to. I have not noticed any rubbing of tires on components
with the 215/70's on the car. If others have what feels like
a wide turning radius, you might want to examine one side of
your rack to see what tabs are used. Apparently rack
rebuilders are not always careful about the VIN number and
rack changes, but I cannot see how the limiters served any
real purpose and, in fact, created a bit of a hazard in my
case when making U-turns."

POWER STEERING PUMP: According to XKs Unlimited,
there have been three different power steering pumps used on
the XJ-S. Prior to 1976‡, the part number was C28457, and
the pulley was retained by a single nut in the center. From
1976‡-1980, part number C45540 was used, and the pulley was
bolted to a hub on the shaft with three bolts. Also, the
high pressure line connection is sealed with an olive,
visible when the hose is removed. From 1980 on, part number
EAC3167 was used and this pump looks just like its
predecessor except that the high pressure line is sealed
with an O-ring. This last pump is referred to as the "metric
pump". The same three units were used on other Jaguars of
similar years.

The XJ-S power steering pump is a standard GM Saginaw
unit. However, it is uncertain whether the Jaguar system
operates at the same pressure as a GM; so, if you replace
the original unit, it is suggested that you remove the
pressure control valve from the Jaguar unit and install it
in the new one. The pressure control valve is easily removed
by removing the outlet fitting and shaking the unit until it
falls out.

POWER STEERING FLUID: You're supposed to put the
same type fluid into the power steering unit that you put
into the automatic transmission. This is interesting, since
the early cars with the Borg-Warner automatics called for
Type F fluid while the later cars with GM400 automatics call
for Dexron II/III, and the power steering system didn't
change. Apparently any ATF will do in the power steering
system.

Apparently Type G fluid was called out in some owner's
manuals for the power steering. "Type G is an obsolete
designator for Dexron. It's so obsolete that nobody
remembers what it was."

REAR END ALIGNMENT: There's no such thing as
castor on non-steering wheels, and toe-in is not adjustable
on the rear of the XJ-S; if it's off, something is bent. The
only alignment adjustment available at the rear is the
camber, adjusted by replacing shims between the inner end of
the axle and the brake disk. The more shims put in, the more
the top of the rear wheel tilts outward.

Note that there are usually some shims between the brake
disk and the differential unit. These are to locate the disk
properly between the calipers, but also affect the camber as
well. If working in this area, always make sure all shims
are reinstalled properly.

Randy Wilson offers this advice: "Camber is not a
constant. The camber control is taken on two pivoted arms
(of unequal length) so that the camber can change on a
predetermined curve based on suspension position.

"It is very unlikely for the camber to change from
factory specs unless one of three things happens: either
something is bent, someone left some shims out during a
differential or brake service, or the ride height is wrong.
The #1 cause is the last, sagged rear springs. So, when you
are told that the rear camber is off, investigate the static
ride height before investing a lot of time/money in shim
swapping."

REAR SUSPENSION
SUBFRAME/DIFFERENTIAL REMOVAL: To work on the
differential, as well as many major tasks relating to the
rear brakes, it is necessary to lower the entire rear
suspension assembly out the bottom of the car. Fortunately,
this is nowhere near as difficult as it appears. Jan
Wikström says "You need two good stands and a small
garage jack, as well as a friend to stabilise the subframe
as you move it down and up (and help you lift it to the
workbench; that sucker is heavy). To make the job a
lot easier, take the spring/shock units out first and refit
them last. You'll need to shift the subframe in two lifts,
as the stroke of the jack won't be long enough. I use a 5"
thick wooden block on the jack and rest the unit on two
cement blocks halfway up."

Some others have reported good results with putting the
wheels back on during removal; that way, the assembly can be
rolled out from under the car. It will require positioning
the car on even taller stands, though.

REAR SPRING/DAMPER DISASSEMBLY: The obvious way to
disassemble the springs from the dampers on the rear end is
to remove the damper with the spring installed, then use a
spring compressor on the bench to separate them. However,
Ian Macfarlane provides an alternative procedure: "To change
the rear shock absorbers without using a spring compressor,
the springs can be held in the compressed state by fitting
four elongated "C" shaped brackets (two per spring) over the
centre 80% of the spring with the car jacked up under the
suspension (preferably with a load in the rear of the car to
maximize spring compression). Then, when the car is jacked
up under the body, the springs will remain partly compressed
and the shock absorbers can be replaced relatively
easily."

REAR WHEEL BEARINGS: According to Chad Bolles, the
bearings in the rear wheel carriers are a Bower/BCA part
number 18590-18520 for the inner, and 18690-18620 for the
outer; available in any auto parts store.

REAR AXLE FAILURE: Jan Wikström reports on
his problem and solution: "The stub axle in the hub carrier
(the bit that turns in the rear wheel bearings) is splined
for the hub and has a large thread and castellated nut on
its outer end. This thread comes right down to the splined
part with no fillet whatever and creates a horrendous stress
concentration at the end of the thread. Mine suffered a
fatigue fracture in consequence; my local parts pusher tells
me this is not uncommon, as one would expect from such an
elementary error, especially if the nut is overtightened.
Accordingly, I ground and polished a shallow rounded groove
at the base of the thread of the new part... (see Figure
10 and Figure
11, illustrations graciously provided by
Wikström).

"The next time you do the rear wheel bearings or
U-joints, I strongly recommend having the stub axles checked
and modified; any competent engineering shop will know about
stress relief. Modifying parts of the Jaguar may be
sacrilege to some of us, but fine as the design is, it isn't
perfect..."

If the stub axle has already broken, it is possible to
fix it by drilling and tapping a hole in the end and using a
bolt and washer instead of the nut. GT Jaguar offers a grade
8 bolt and a specially designed washer for this purpose,
although you could conceivably come up with suitable parts
from local sources. This fix may also be used as a
preventative measure, since cutting off the stub and
drilling for the bolt eliminates the stress concentration in
the original part as well as the shallow groove does.

Perhaps one thing to note is that GTJ offers these parts
at all; that would seem a serious indicator of just how
common this problem is, and how important it is to address
it.

REAR HUB CARRIER CRACKING: Joe Bunik reports that
the cast aluminum hub carriers on his car cracked in the
area just above and outward of the fulcrum shaft. The crack
was parallel to the fulcrum shaft, but just far enough above
it to be in the structural portion between the fulcrum shaft
bearings and the wheel bearings. According to his mechanic,
this is not an unusual problem.

Folks, if this part breaks at speed, you will be
taking the Lord's name in vain! These parts are expensive,
but if a crack is found it would be foolish indeed not to
address it.

What with the rough surface on the cast aluminum combined
with the dirt and grime normally covering it, it is entirely
too easy not to notice a crack like this. Whenever a rear
wheel is removed, it is recommended that the hub carrier be
cleaned up a little and inspected for cracks, especially in
the area just above the fulcrum shaft.

Wheels
and Tires

SPOKE WHEELS: Yes, a Jaguar with
real spoke wheels really looks good. Unfortunately, it
generally doesn't drive worth a hoot. The spoke wheels
available have a reputation for trouble. Spoke wheels were a
good idea in the ë50s when Jaguars needed to maximize
air flow to cool their brakes. Since that time, two changes
have conspired against spoke wheels:

1. The advent of tubeless tires. Many spoke
wheels won't work with tubeless tires, so you must
install a tube. A tube installed in a speed-rated tire
(the XJ-S should be fitted with V-rated tires) completely
negates the rating, and renders the tire unsafe at speed.
Don't drive fast with inner tubes in your tires!

2. The advent of low, wide tires. A spoke wheel is a
reasonable structure when it's tall and skinny, like a
bicycle wheel or the automobile wheels of the ë50s.
But it is a structurally poor design for modern low, wide
wheels.

Furthermore, modern Jaguar wheels need an offset
(distance from mounting surface to centerline of wheel) of
around 1º", which is not conducive to spoke wheel
strength.

Spoke wheels tend to need truing on a regular basis. This
is not a job for the home mechanic, and finding someone who
can do it is a challenge. Often the wheels must be returned
to the manufacturer for truing. Obviously, whoever does it,
this process will also require rebalancing because the wheel
is not the same shape as it was.

Spoke wheels generally have chrome-plated steel rims,
leading to rust problems, flaking chrome, and associated
leakage at the tire/rim seal.

By the way, if it's a weight reduction you expect, forget
it. There is nothing lightweight about spoke wheels.

It should also be noted that since the spoke wheels are
more flexible than alloy, the handling will suffer somewhat.
With a car this heavy, the difference in the way the car
corners is noticeable. You may even get sounds, as the
spokes strain and creak with the load.

ALLOY WHEELS: The specified torque on lug nuts on
earlier Jaguar alloy wheels is 45-50 ft-lb., and 75 ft-lb.
on later ones. This impresses some people as not being very
tight. However, higher torque is unnecessary and causes
damage to the aluminum wheels; this is true of all alloy
wheels, and in this day and age your tire store should know
better. If the shop installs your wheels with an air wrench,
tell them where to get off and take your business
elsewhere.

There are now machines in better tire stores that mount
tires on wheels by gripping the wheel from the inside with
soft grippers and never touching the wheel's pretty outside
surface. Check out the price lists for new Jaguar alloy
wheels and decide for yourself if it's worth finding a store
with this equipment.

You might also want to watch how the wheels are mounted
on the balance machine.

ALLOY WHEEL SEIZING: Believe it or not, one of the
places where Jaguars are known to have seizing problems is
between the alloy wheel and the hub. Robert Woodling
suggests use of anti-seize compound on the mating surfaces,
especially at the hole in the center of the wheel. It can be
disconcerting to have a flat tire and be unable to get the
wheel off.

WHEEL BALANCING: Incompetence is rampant in the
retail tire industry -- at least in Florida. Left to their
own devices, most of the meatheads in a tire store will
happily static balance your Jaguar alloy wheels, then beat
the weights onto the rim with a hammer.

There are two basic types of imbalance. The old-fashioned
bubble balancing, which engineers refer to as static
balancing, only corrects one type of imbalance -- the type
that causes the wheels to hop. This is generally adequate
only for wheels that are very narrow, and should be
considered unsatisfactory for any modern automobile.

The other type of imbalance, dynamic imbalance, is the
type that causes wobble. A wheel that is statically balanced
may still be dynamically imbalanced by having a heavy area
on the outside edge of the wheel and an equivalent heavy
area 180 degrees away on the inside edge. Although the wheel
would appear balanced on a bubble machine, when spinning the
two diagonally opposite heavy areas cause the wheel to
wobble. It's usually not too noticeable on the rear wheels,
but on the front wheels it can cause steering wheel shudder.
And you may eventually wanna rotate the rear wheels to the
front, so it's kinda nice to have them all correct.

To correct a dynamic imbalance requires that weights be
placed in two separate planes -- usually (but not
necessarily) the inside and outside edges of a wheel. It
requires more lead than static balancing. It also requires a
machine that actually spins the wheel; the bubble balancer
is out. Use of these machines has come to be called
"computer balancing". However, note that a switch on the
machine allows the operator to specify a static balance
only, so asking for "computer balancing" does not guarantee
a proper dynamic balance.

The meatheads generally understand that the owner of
alloy wheels is not thrilled about balance weights on the
visible outside surface of the wheel. The standard response
is simple: he sets the balance machine on "static" and
applies all the balance weights to the inside rim of the
wheel. This actually makes the dynamic imbalance worse,
since even in the days of the bubble balancer the operator
knew to put half the weight on the inside edge and half on
the outside.

Insist on watching what is going on. There is a button
marked "static" usually at the top left on the machine, with
a red indicator light. When on, the machine will read
imbalance values on the left indicator and a blank display
on the right indicator. If you see this happening, I highly
recommend you have your wheels put back on your car and take
your business elsewhere.

The balance weights needed are part of the problem. Steel
wheels commonly use "clip-on" weights that are hammered onto
the rim. Some alloy wheels are designed with a rim that can
accommodate clip-on weights, but they may not attach as well
to the thicker aluminum. And use of a hammer to install is
not good for aluminum, especially if the meathead responds
to difficulty with a bigger swing.

When the steering on an XJ-S is turned full lock, the
clearance between the inside edge of the wheel rim and the
front anti-roll bar is very small. If wider-than-original
wheels are used, clip-on balance weights may actually hit
the bar, resulting in a blip-blip-blip as you roll around a
tight turn.

The proper balance weights to use on alloy wheels are
called "stick-on", and are attached to the inner surface of
the wheel with a layer of foam tape attached to the back
side of the lead weight. One problem is that they are not
reusable; once peeled off, the tape is not reusable, and the
shops customarily throw them away. I guess using generic
foam tape has not occurred to them, or just isn't worth it,
even though they often complain loudly that these weights
are expensive and charge the customer accordingly.

The problem is exacerbated by the meathead not knowing
how to use the machine properly and having to do a
by-guess-or-by-gosh balance job. With the clip-on weights,
he can just keep prying them off and reinstalling them until
he gets it right, but he can waste a lot of stick-on
weights. An intelligent operator, of course, will be able to
set the machine up properly and get the correct weight
applied the first try.

The older computer balance machines were really designed
for steel wheels. They have a setting for the width of the
wheel and assume you will be putting clip-on weights on the
edge. While the machines have a setting labeled "Mag", it is
unlikely the operator will know how to use it. If you are
using stick-on weights (which are located radially inward
and on different planes than clip-on), the machine must be
set up properly in order to read the correct amount of
weight required. Simply setting the same width, offset and
diameter info as used on the steel wheels will indicate if
the wheel is imbalanced but will give incorrect data on the
size balance weights needed, so the operator will be making
several attempts.

There are newer balance machines that better accommodate
alloy wheels. They can properly balance the tires by
applying weights in any two planes, not necessarily the
outer edges; the desired location for the weights is a
separate setting in the balance procedure. They also can
"split" a large balance weight requirement into two smaller
weights, telling the operator where to put them both. This
is helpful for two reasons: first, a large stick-on weight
means a long stick-on weight, and as it curls around
the rim its effective radius reduces somewhat, and the
balance becomes inaccurate. Second, using two smaller
weights may allow the operator to hide them behind spokes on
some wheels.

Owners of alloy wheels should always insist on dynamic
balancing using stick-on weights in two planes within the
wheel -- one near the inner edge, and one just inside of the
outer face of the wheel. Since these planes are closer
together than the edges of the wheel, even more lead will be
required to correct imbalances. But the weights won't show,
and nobody will need to use a hammer to install them. Always
insist that the balance machine shows 0.00 on both
indicators before the balance is acceptable.

The only real problem with stick-on weights is a
reputation for getting lost. Since clumps of mud and other
debris sometimes gets dragged around the inside of the
wheel, the foam tape can be ripped away. Two suggestions are
in order, and neither is likely to be done by the tire shop,
so the owner should bring the materials necessary and do
them himself while the wheels are off: First, mark the
locations of the stick-on weights with a permanent marker.
Then, secure them with a piece of aluminum tape (available
at air conditioning shops). Duct tape is not good; it
quickly dries up and falls off, often taking the balance
weight with it. The aluminum tape appears to be light enough
to not affect the balance when added; or, to be safe, you
could simply add a dummy piece of tape on the opposite side
of the wheel.

WHEEL INTERCHANGABILITY: A few years back when
Jaguar introduced the Anti-lock Braking System (ABS), they
also introduced the new faux spoke pattern alloy wheels.
Some reports at the time suggest these changes were related;
apparently, the older wheels (a domed 5-spoke alloy design)
interfered with the ABS hardware. The bolt pattern, offset,
width, and other dimensions remained unchanged, so the later
wheels can be used on earlier cars. But if the reports are
true, the earlier wheels cannot be used on later cars.

XJR-S: John Goodman reports that the XJR-S uses
"8" wide special alloys (the front and back wheels are not
interchangeable because of different offsets)."

TICK, TICK, TICK: William C.W. Lamb had an
irritating tick from one of his wheels. He was all set to
tear into bearings when Roger Homer pointed out that it may
just be the Jaguar logo in the center of a wheel cover
coming loose. "Pulled both hubcaps - it was the kitty
on the right rear. Quick fix with duct tape and some black
RTV!"

TIRES: The early US-spec XJ-S
was fitted with 215/70VR-15, and the later models with
235/60VR-15 tires. The wider tires are slightly smaller in
diameter than the earlier, but there is no indication that
Jaguar altered the speedometer or suspension. Both sizes are
very suitable for the car, and there is normally no reason
to select tires beyond these sizes. 16" wheels were also
fitted to some later cars.

When replacing tires as a set, you don't have to stick
with the brand of tire that came on the car. In fact, it may
be better to change brands according to Michael Neal, who
works on Jaguars for a living: "I've seen hundreds of the
215/70 Pirelli P5s rip out at the sidewall near the bead.
These are the original equipment tires on the US-spec XJ6
Series 3s and early XJ-S's. Sorry, but I would not even
consider buying a set of these. The 235/60 P600s had the
same problem."

You should insist on at least a V-rating (a speed rating
of 220 Km/h, or 137 mph) unless you always obey the US speed
limits. In some countries, you are required by law to use
V-rated tires on these cars. The rating is either indicated
within the tire size, as in 215/70VR-15, or elsewhere
on the sidewall, as in a 98V adjacent to the tire
size. Other ratings include S (180 Km/h or 112 mph), T (190
Km/h or 118 mph), H (200 Km/h or 124 mph), and Z (250 Km/h,
or 155 mph), and new speed ratings higher than Z seem to be
introduced on a regular basis. In the US, if there is no
indication of speed rating, the tire is S-rated.

These ratings are intended to indicate suitability for
Autobahn-style driving -- continuous high speed. Generally,
the limiting factor is heat buildup in the tire.
High-speed-rated tires either run cooler or are made of
higher-temperature material, or both. Much of the heat
generated is dissipated to the air inside the tire and away
through the rim, so inner tubes invalidate the ratings (the
flexing of the inner tubes themselves adds to the
heat buildup). There are also concerns about how patching
holes affects speed ratings; it is recommended that the
owner check the literature that comes with the tires before
opting for a low-cost "plug" repair to his tires.

Since the flexing of the tire is what generates the heat,
tire manufacturers usually achieve a high speed rating by
making the sidewalls stiff. Therefore, the high-speed-rated
tires drive differently than normal tires, even at low
speed. For this reason, many recommend the V-rated tires
even to those who don't drive fast. This is especially true
for the XJ6 and XJ-S, because the soft suspensions get
downright mushy with the softer, lower rated tires. There
are reports that S-rated tires used on these heavy cars will
flex so much that they will wear out quickly.

The heat buildup due to tire flexing is also the reason
you must have fully inflated tires when driving fast, as
indicated in the XJ-S glovebox.

As the tread wears, the speed rating of the tire will
actually improve. A thinner carcass generates less heat when
flexing, and dissipates heat better. There have been
promotions claiming street tires were successfully used for
racing; in these cases, typically the outer half of the
tread was shaved off before the tire was even put on the
car.

One other thing to consider when replacing tires is the
intentions of the tire design. The original Pirelli P5's
were designed for a soft ride, and the Z-rated 235/60
Goodyear Eagle NCT's fitted to the later XJ-S reportedly
also provide an excellent ride -- actually an impressive
achievement when maintaining a V or Z rating. Most V-rated
tires are designed more for performance than ride, and
replacement with such tires is likely to result in vastly
better performance and road feel but a less luxurious ride.
A set of Dunlop SP Sport D40 M2 235/60-15's (unidirectional
tread, max pressure 44 psi) convert the XJ-S from a luxury
coupe into a GT. Similar results have been reported with
Yokohama performance tires.

Note that the Pirelli P5's are not available any more,
and reportedly the Goodyear Eagle NCT's have stopped
production as well. In fact, Bill Weismann reports that
Goodyear makes nothing V-rated or better in 215/70R-15 or
235/60R-15, and their dealers will often try to sell you a
lower-rated tire.

For those who'd like to know, the rest of the tire size
code works like this: The first three digits, such as 215,
is the width (mm) of the tire at the widest point -- the
middle of the sidewall. It is always rounded to a number
ending in 5. The two digits after the slash, along with an
implied decimal point, gives the aspect ratio: the height of
the tire above the rim divided by the width described above.
For the 215/70VR-15, this is .70, and the height of the
tread above the rim is 215 x .70 = 150mm. If there is no
aspect ratio indicated within the tire size, the aspect
ratio is .80. The R in the tire size merely indicates it is
a radial tire; it is sometimes omitted. The -15 indicates it
fits a 15" wheel.

The one thing you normally don't want to change is the
overall diameter of the tire, since this would affect your
speedometer and odometer readings as well as your ride
height. Changing the ride height can have adverse effects on
the suspension geometry, even if you don't mind the altered
ground clearance. To maintain overall diameter when you go
to a wider tire, you also have to change the aspect ratio to
a lower value. Tire manufacturers also usually list a
"loaded radius", the distance from the ground to the center
of the wheel with weight on it. This measurement is meant to
include the deformation of the tire under load so the
consumer can determine the actual ride height.

David Littlefield suggests you also check http://www.tires.com
"This is the website for Discount Tires Direct, an online
version of Discount Tires stores. The Discount Tire site
will allow you to look up the right size tire for your
vehicle. It gives prices for most tires, although for some
reason not for Michelins. You have to call their 800 numbers
for those."

Do not mix tire types, sizes
or makes on a Jaguar. The XJ-S and the XJ6 have a suspension
design in which the entire suspension assemblies are
attached to the car with flexible mounts, and the relative
stiffness of the mounts is premised on all the tires being
the same. Mixing tire types, even outwardly similar ones,
can result in dangerous instabilities in this suspension
system. This is no joke; having one type of perfectly good
tire on one end and another type of perfectly good tire on
the other can result in you being rudely introduced to a
tree when you aren't even traveling that fast.

TIRE PRESSURES: John Goodman says, "Most of us
here (UK) have long junked our 15" wheels and run 16" or 17"
rims, but the less competitive drivers, or those who do a
lot of city streets always keep the tyre pressures down
quite a bit. We run them up to 8psi lower than the handbook
stated figures. My handbook says 35psi front and 32psi rear,
so I run at 30 front and 27 rear. On 245/50 or 225/55 x 16"
this gives only very slight loss of handling at
extremes of cornering, but a very noticeable improvement in
ride comfort. Has no effect on tyre wear either. This was a
local Jaguar dealer recommendation!!!" Note: perhaps a
workable plan for those who value ride quality, but high
continuous speeds should be avoided without full pressure.
Also note that lower pressure will provide less protection
for your rims, so don't drive over curbs at speed.

Interestingly, the earlier XJ-S's took the opposite tact,
and recommended rather low tire pressures (on narrower tires
to boot!) and then recommended you go to higher pressures if
driving fast. Perhaps the recommended pressures on Goodman's
car are due to it being an XJR-S, and a sportier ride and
high speeds are assumed.

Regardless of the peculiarities of one XJ-S vs. another,
one thing must be pointed out: the nearly religious devotion
many automobile owners pay to the "recommended tire
pressures" is completely uncalled for. As long as you
don't exceed the pressure limit written on the side of the
tire itself, tire pressures can be varied considerably to
provide the owner with the desired performance and ride. If
the balance doesn't seem right to you, you can also vary the
front/rear pressure distribution to alter it.

For optimum tire wear, an excellent plan is to keep an
eye on the wear at the edges of the tires vs. the center. If
they're wearing faster in the center, lower the pressure; if
they're wearing faster at the edges, raise the pressure.
This helps configure the car for the owner's driving style,
since a driver that corners hard will scrub the corners of
the tire more and should be using higher pressure. It
even helps compensate for drivers that dive into turns as
opposed to drivers that accelerate through turns, since the
different styles will cause different tire wear patterns and
correspondingly altered pressures. Of course, bad alignment
or other complicating factors can easily screw up the
data.

If you can't tell, the XJ-S is nose heavy, and one would
expect that the front tires will always need more pressure
than the rears -- unless you're carrying sandbags around in
the trunk.

WINTER TIRES: In some states, you are required by
law to have either snow tires or "all season" tires on your
car during the winter months. According to Bill Weismann,
"For a tire to be labeled "All-Season" it must be labeled
(By federal law...) "M+S" on the sidewall. The only tire
that properly fits the XJ-S in this size (Radial
T/As, for example, are all-season, but are of a grossly
lower speed rating) that is an all season is the Comp T/A
VR4. Believe me, these things are terrible in the snow;
OTOH, P600s are actually decent in the snow for a
summer-compounded tire.

"It's a lot more than tread design that qualifies a tire
as an all-season; the main problem with High Performance
tires is that they have to be at somewhat high temperatures
in order for them to "stick". An all-season tire usually
offers two features for it to work in the snow.

1) A tread compound that will remain pliable in
the cold (below 40† F or so..)

2) A tread design that will work in snow. Look at,
say, a Comp VR4 vs a D40M2, you'll see that the D40's
tread design consists of mostly large blocks, while the
Comp's tread design is broken up a lot more. I have owned
both and can assure you that the D40M2 (For reasons other
than this btw..) will easily outhandle the Comp VR4. I
also know from personal experience that the D40M2 is like
a racing slick in the snow."

If you choose to purchase a separate set of snow tires
for the winter, you should also note that, in snow, the
narrower the tire, the better. For the XJ-S, you'd want to
go back to the 215/70R-15's, and possibly even to a 195R-15.
You also, of course, will want to find some really junk
wheels, since snow, sand, and salt make alloys look really
crummy very quickly.

You might also wish to carefully consider your options.
Winter driving often involves snow, ice, and mud -- as well
as a far portion of nice, clean pavement, since many road
departments are really good at keeping roads clear.

One highly-rated type of snow tire is called a Blizzak
which has a porous compound that grabs snow and holds on
until it looks like your tires are made of snow; they work
really well on dry snow, but are reportedly not much good in
mud, wet snow, ice, or dry pavement, and they wear quite
rapidly on dry pavement.

Studs are another option that the owner might regret.
Great on ice, but not particularly beneficial anywhere else.
Also, they will damage pavement, so they are frowned upon or
downright banned in some areas. They also seem to have a
detrimental effect on the rolling resistance of the car, so
your fuel economy gets much worse and the car feels like the
brakes are dragging or something.